Is x+1 a factor of 12? : GMAT Data Sufficiency (DS)
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# Is x+1 a factor of 12?

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Is x+1 a factor of 12? [#permalink]

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09 Sep 2010, 09:20
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Is x+1 a factor of 12?

(1) x+1 is even
(2) x+1 is a factor of 2 and 3
[Reveal] Spoiler: OA
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09 Sep 2010, 09:29
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agnok wrote:
Is x+1 a factor of 12?

1. x+1 is even
2. x+1 is a factor of 2 and 3

Good question.

(1) x+1 is even --> clearly insufficient, x+1 could be 2 or 30.

(2) x+1 is a factor of 2 and 3 --> 2 and 3 are consecutive integers, consecutive integers are co-prime, which means that they do not share ANY common factor but 1 (for example 5 and 6, two consecutive integers share only one common factor: 1). So as x+1 is a factor of BOTH 2 and 3 then x+1=1 and 1 is a factor of 12. Sufficient.

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09 Sep 2010, 09:40
Thanks.. I had got confused between multiple and factor in statement 2... realized this basic goof after reading your post.
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09 Sep 2010, 18:24
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divisor, multiple and factor can be tricky when we are short of time...best is to write factors..

Question is Is x+1 = 1,2,3,4,6,12?
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21 Dec 2012, 03:05
Bunuel wrote:
agnok wrote:
Is x+1 a factor of 12?

1. x+1 is even
2. x+1 is a factor of 2 and 3

Good question.

(1) x+1 is even --> clearly insufficient, x+1 could be 2 or 30.

(2) x+1 is a factor of 2 and 3 --> 2 and 3 are consecutive integers, consecutive integers are co-prime, which means that they do not share ANY common factor but 1 (for example 5 and 6, two consecutive integers share only one common factor: 1). So as x+1 is a factor of BOTH 2 and 3 then x+1=1 and 1 is a factor of 12. Sufficient.

Bunuel,

The reason I chose E was because of the case where x = 5

x + 1 - even
x + 1 = 6 is factor of both 2 & 3

But 12 is not a factor of 6
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21 Dec 2012, 03:09
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eaakbari wrote:
Bunuel wrote:
agnok wrote:
Is x+1 a factor of 12?

1. x+1 is even
2. x+1 is a factor of 2 and 3

Good question.

(1) x+1 is even --> clearly insufficient, x+1 could be 2 or 30.

(2) x+1 is a factor of 2 and 3 --> 2 and 3 are consecutive integers, consecutive integers are co-prime, which means that they do not share ANY common factor but 1 (for example 5 and 6, two consecutive integers share only one common factor: 1). So as x+1 is a factor of BOTH 2 and 3 then x+1=1 and 1 is a factor of 12. Sufficient.

Bunuel,

The reason I chose E was because of the case where x = 5

x + 1 - even
x + 1 = 6 is factor of both 2 & 3

But 12 is not a factor of 6

6 is NOT a factor (divisor) of neither 2 nor 3.
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21 Dec 2012, 03:14
Yes, I mixed multiple and factors and made a massive mess.

Thanks Bro. Much appreciated.
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Re: Is x+1 a factor of 12? [#permalink]

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21 Dec 2012, 05:13
Hi everyone!

I might've missed something. But I got a question.

Isn't statement (1) contradicting statement (2)?

(1) -> x+1 = even

(2) -> x+1 is a factor of 2 and 3. (Which gives us x+1 = 1)

Wouldn't that mean that statement (1) is false?

Again, I might've missed something.
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Re: Is x+1 a factor of 12? [#permalink]

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21 Dec 2012, 05:24
Hiho wrote:
Hi everyone!

I might've missed something. But I got a question.

Isn't statement (1) contradicting statement (2)?

(1) -> x+1 = even

(2) -> x+1 is a factor of 2 and 3. (Which gives us x+1 = 1)

Wouldn't that mean that statement (1) is false?

Again, I might've missed something.

Not at all

6,12,18,24,36...

all are even numbers which have factors as 2 & 3
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Re: Is x+1 a factor of 12? [#permalink]

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21 Dec 2012, 05:50
eaakbari wrote:
Hiho wrote:
Hi everyone!

I might've missed something. But I got a question.

Isn't statement (1) contradicting statement (2)?

(1) -> x+1 = even

(2) -> x+1 is a factor of 2 and 3. (Which gives us x+1 = 1)

Wouldn't that mean that statement (1) is false?

Again, I might've missed something.

Not at all

6,12,18,24,36...

all are even numbers which have factors as 2 & 3

I'm not quite sure that I understand.

x+1 is a factor of both 2 and 3. The only factor 2 and 3 shares is 1. Therefore x+1 = 1.

Now what I don't understand is why statement (1) says that x+1 is even, when statement 2 gives us the solution that makes its odd.
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Re: Is x+1 a factor of 12? [#permalink]

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21 Dec 2012, 06:08
Hiho wrote:
eaakbari wrote:
Hiho wrote:
Hi everyone!

I might've missed something. But I got a question.

Isn't statement (1) contradicting statement (2)?

(1) -> x+1 = even

(2) -> x+1 is a factor of 2 and 3. (Which gives us x+1 = 1)

Wouldn't that mean that statement (1) is false?

Again, I might've missed something.

Not at all

6,12,18,24,36...

all are even numbers which have factors as 2 & 3

I'm not quite sure that I understand.

x+1 is a factor of both 2 and 3. The only factor 2 and 3 shares is 1. Therefore x+1 = 1.

Now what I don't understand is why statement (1) says that x+1 is even, when statement 2 gives us the solution that makes its odd.

Yes , you are correct.

Maybe statement B should read 'x+1 has factors 2 and 3'

Its probably not a good source.

Let Bunuel solve this confusion...XD
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Re: Is x+1 a factor of 12? [#permalink]

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21 Dec 2012, 06:27
eaakbari wrote:
Hiho wrote:
eaakbari wrote:

Not at all

6,12,18,24,36...

all are even numbers which have factors as 2 & 3

I'm not quite sure that I understand.

x+1 is a factor of both 2 and 3. The only factor 2 and 3 shares is 1. Therefore x+1 = 1.

Now what I don't understand is why statement (1) says that x+1 is even, when statement 2 gives us the solution that makes its odd.

Yes , you are correct.

Maybe statement B should read 'x+1 has factors 2 and 3'

Its probably not a good source.

Let Bunuel solve this confusion...XD

I think it would be better if (1) would read ' x+1 = odd' instead.

Your statement would make the question unsolvable because x+1 would have too many possible outcomes.
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21 Dec 2012, 19:20
Bunnel according to statement1 X+1 is even but in our second statement we have derived X+1=1 which is an odd number .In real GMAT questions i do u think this kind of contradiction will be there in the two statements given ???
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Re: Is x+1 a factor of 12? [#permalink]

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21 Dec 2012, 20:12
Hiho wrote:
Hi everyone!

I might've missed something. But I got a question.

Isn't statement (1) contradicting statement (2)?

(1) -> x+1 = even

(2) -> x+1 is a factor of 2 and 3. (Which gives us x+1 = 1)

Wouldn't that mean that statement (1) is false?

Again, I might've missed something.

x+1 is a factor of both 2 and 3 that means the sum of x+1 can divide both 2 and 3 three. You see three no value common that divide both 2 and 3 other than 1 .
12 is also divisible by 1.
Ans. B
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22 Dec 2012, 04:23
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skamal7 wrote:
Bunnel according to statement1 X+1 is even but in our second statement we have derived X+1=1 which is an odd number .In real GMAT questions i do u think this kind of contradiction will be there in the two statements given ???

On the GMAT, two data sufficiency statements always provide TRUE information and these statements never contradict each other.

(1) should read: x+1 is odd.

Hope it's clear.
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Re: Is x+1 a factor of 12? [#permalink]

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03 Mar 2014, 12:18
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Re: Is x+1 a factor of 12? [#permalink]

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04 Mar 2014, 05:30
Option B.
S1: If x+1 is even
x+1 could be 2 in which case answer is yes.
x+1 could be 14 in which case answer is no.
Not suff.

From S2:x+1 could only be 1,2 or 3 each of which is a factor of 12.So answer is yes.Suff.

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Re: Is x+1 a factor of 12? [#permalink]

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12 Mar 2014, 04:15
agnok wrote:
Is x+1 a factor of 12?

(1) x+1 is even
(2) x+1 is a factor of 2 and 3

Statement I is insufficient:

x + 1 = 8, x + 1 = 4

Statement II is sufficient:

If x + 1 is a factor of 2 and 3 it has to be equal to 1. Hence x + 1 is a factor of 12
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Re: Is x+1 a factor of 12? [#permalink]

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13 Nov 2015, 23:31
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Re: Is x+1 a factor of 12? [#permalink]

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16 Mar 2016, 09:06
Excellent Question
here statement 1 is not sufficient as x+1 can be 8 or 2 or 500
statement 2 tells us that x+1 is a factor of both 2 and 3
hence x+1=1 => x=0
thus as one is the FACTOR of every number => sufficient
hence B
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Re: Is x+1 a factor of 12?   [#permalink] 16 Mar 2016, 09:06
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